Method of heat treating porcelain



Aug. 11, 1925.

F. S. M CULLOUGH METHOD OF HEAT TREATING-PORCELAIN Filed March 21, 1925ATTORNEY Patented Aug. 1-1, 1925.

v UNITED STATES PATENT OFFICE.

Israel) or near rana'rmo roacuam.

' Application fled me. 21, m5. semiiro. 11,200.

To all whom it may concern.- Be it known that I, FREDERICK S. McCUL-LOUGH, a citizen of theUnited States, re-

- siding at -Wilkinsburg, in the county of Allegheny and State ofPennsylvania, have invented certain new and useful Improvements inMethods of-Heat Treating Porcelain, of which the following is aspecification.

This invention relates to a method of firing or heat treating porcelainor similar earthen substances. F

In certain electrical and other devices for scientific and commercialuse, it is desirable to have a porcelain of extremely fine ade. Theobject of the present invention 1s to provide a method of heat treatingor firing porcelain wherein the porcelain may be subjected to extremelyhigh temperatures in a vacuum, whereby a porcelain of very fine grademay be obtained, and a porcelain suitable for various purposes of ascientific nature can be produced.

The invention contemplates the firing of the porcelain either in anevacuated vessel in which the porcelain is, permanently mounted foruse,or. the heat treating of porcelain in a vessel from which it maybesubsequently removed for use in various devices.

The invention may be readily understood by reference to the accompanyingdrawing illustrating diagrammatically the method which the presentinvention contemplates. It will be understood that the invention is not.restricted to the. particular devices or apparatus shown, the drawinbeing merely for the purpose of illustration. In the drawings:

Fig. 1 represents a vertical section through a vessel' having aporcelain rod therein, and having elements associated in the vessel.

therewith for efiecting the process;

Fig. 2 represents a transverse section on line II-II of Fig. 1; and vFig. 3 is a view similar to Fig. 1, showingz-a slightly modifiedarrangement.

eferrmg to Figs. 1 and 2, 5 designates a suitable envelope which mayhave a perma- 8 that maybe-carried by the plug 6, is a metallic sleeve9, into which is set or fitted a raw or partially fired porcelain orother earthen rod 10. Surrounding the vessel 5 is a' coilll which may beconnected with a high frequency alternating circuit designated w. i p

In practicing the invention; the porcelain rod is mounted inside themetal sleeve 9, as above described, and a current of high frequency isthen passed through the external coil 11.' The alternating fieldroducedby the coil will serve to induce .e dy currents in the metalsleeve 9,heating the sleeve to 'an extremely high temperature. This heatwill, of-course, be transmitted both b conduction and radiation to theporcelain rod 7 10, serving to fire theporcelain. During the .firingoperation, an extremely high vacuum may be maintained within the vessel.If the porcelain is to remain in the vessel permanently, the outlet 7may be sealed off upon completion of the firing operation.

In the arrangement shown in Fig. 3, the method is substantially similar.In this figure, 12 designates the envelope, 13 the plug at the baseof-the envelope, 14 is the connection to the exhaust line, and 15 is thesupporting stem in the base or plug which carries the metal cylinder 16;The ,porcelain rod 17 is inserted in the tube 16.

Surrounding the tube 16 and spaced therefrom, there may be a second tube18 of larger diameter. This second tube may be carried on a suitablesupport, such as 19. Surrounding the envelope is the coil 20 connectedin the high frequency circuit including a source :0. p

With the arrangement shown in Fig. 3, the external cylinder 18 will beheated to an extremely high temperature by the introduction of eddycurrents therein when the external coil is energized. Heat from thisplate or tube will be radiated and concentrated on theinner tube 16, bymeans of which the porcelain rod 17 will be hi hly heated. During thepractice of this/met 0d,-

shell, mounting the shell in a; vessel, maintaining a vacuum in thevessel, and heating the metal shell while the same is maintained in avacuum.

2. The method of firing porcelain which consists in placing theporcelain within a metal receptacle inside of an evacuated vessel, andmaintaining an alternating current field about the vessel to heat saidmetal receptacle. v

3. The method of heat treating porcelain which consists in surrounding abody of porcelain with a metal casing, mounting said casing within avessel, connecting the vessel with an exhaust line exhausting thevessel, and heating the metal casing and porcelain while the vessel isconnected with the exhaust line.

4;. The method of heat treatin porcelain which consists in placing aporce ain rod inside a metal cylinder, mounting said cylinder and rodwithin a vessel, connecting said vessel to an exhausting pum exhaustingthe vessel, and heating the cy inder and the porcelain by means of anexternal coil.

5. The method of heat treating porcelain which consists in forming aporcelain rod, enclosing the porcelain rod in a metallic cylinder,mounting such cylinder and rod inside a vessel, surrounding the cylinderand rod with a second cylinder, connecting said vessel with an. exhaustpump exhausting the vessel, and maintaining an alternating current fieldwithin the tube to heat the metal cylinders and the porcelain within thetube; I

In testimony whereof I hereunto aflix my signature.

FREDERICK S. MCCULLOUGH.

